Machine for grinding the back-off from the cutting edges of tools of the broach type



, S. G- BRADY MACHINE FOR GRINDING THE BACK-OFF FROM THE Ndv. 22, 1960 CUTTING EDGES OF TOOLS OF THE BROACH TYPE Filed Jan. 28, 1957 5 Sheets-Sheet 1 INVENTOR.

ATTORNEYS Nov. 22, 1960 s. G. BRADY 2,960,804

WECHINB FOR GRINDING THE BACK-OFF FROM THE eu-rwmcsoczs 0F TOOLS" OF THE BROACH TYPE Filed Jan. 28, 1957 5 Sheets-Sheet 2 INVENTOR.

SAMUEL G BRADY ATTORNEYS Nov 22, 1960 5, BRADY 2,960,804

. MACHINE FOR GRINDING THE: BACK-OFF FROM THE CUTTINGEDGES 05 TOOLS OF vTHE BROACH TYPE Filed Jan. 28. 1957 1 5 Sheets-Sheet 3 FIG.3.Q

INVENTOR.

SAMUEL G. BRADY ATTORNEYS Nov. 22, 1960 5 G Y 2,960,804

BR MACHINE FOR GRINDING THE BACK-OFF FROM THE CUTTING EDGES OF TOOLS OF THE BROACH TYPE Filed Jan. 28. 1957 s Sheets-Shae; 4

INVENTOR.

SAMUEL G. BRADY I ATTORNEYS Nov. 22, 1960 s. s. BRADY 7 2,960,804 I momma FOR GRINDING THE BACK-OFF FROM THE CUTTING noses. 0F TOOLS OF THE BROACH TYPE Filed Jan. 28, 1957 5 Sheets-Sheet 5 S A-H INVENTOR.

SAMUEL G.BRADY ATTORNEYS United States Patent MACHINE FOR GRINDING THE BACK-OFF FROM THE CUTTING EDGES OF TOOLS OF THE BROACH TYPE 9 Claims. (CI. 51-34) The invention relates to grinding machines more particularly designed for grinding the back-off surfaces from the cutting edges of tools of the broach type and also of other multiple cutting edge tools.

It is the object of the invention to obtain a construction in which said back-off may be ground at any selected angle and without interference with any other portions of the tool. To this end the invention consists in the construction as hereinafter set forth.

In the accompanying drawings:

Fig. 1 is a front elevation of the machine.

Fig. 2 is a plan view thereof.

Fig. 3 is an end elevation.

Fig. 4 is a sectional front elevation of the mechanism controlling the grinding operation.

Fig. 5 is a cross section on line 5--5, Fig. 4.

Fig. 6 is a cross section partly in elevation on line 6-6, Fig. 5.

Fig. 7 is a front elevation illustrating the grinding of the back-off on a broach type tool.

Figs. 8, 9 and 10 illustrate varying cross sectional contours of form grinder wheels used in grinding the backoff surfaces of correspondingly contoured broach tools.

The general construction of machine is similar to that of other grinding machines including a bed A, a work table B mounted on said bed and including a headstock B, a tailstock C and centers B, C for engaging opposite ends of the broach tool. D is a carriage mounted on the rear portion of the bed which may be positioned as shown for grinding or in a grinding wheel dressing position. By means of a suitable indexing mechanism (not shown), work table B may be successively moved in increments. Incremental movement of the work table will bring the broach teeth into registration with the. grinding wheel. The construction is as follows:

Mounted upon and projecting upward from the carriage D is a housing E within which is a frame F having aligned hollow trunnions F, F engaging circular bearings E, E in the front and rear walls of the housing E. The frame F includes a pair of generally vertically extending guideways F for a carriage G. The latter has spaced portions adjacent to said guideways F between which extend a pair of guideways G which are in a plane perpendicular to the plane of the guideways F Mounted on the carriage is a motorized grinder unit H including an electric motor H having its rotor shaft H extending outward through the hollow trunnion F and constituting the arbor for a grinder wheel I. This wheel is formed to a cross sectional contour corresponding to that of the cutting edges of the breach. The wheel is also located in the longitudinal plane of the broach mounted on the centers B, C. The frame F is rotatively adjustable on the trunnions F, F through a limited angle and will correspondingly adjust the guideways G to an angle ninety degrees from said guideways F To produce such an adjustment the frame F is connected by a pivotal link F with a screw threaded rod F engaging a nut F rotatively adjustable in a bearing E in the wall 2,960,804 Patented, Nov. 22, 1960 of the housing E. A handle F outside the housing serves to rotate the nut F and thereby adjust the frame F to the desired angle. Mounted on an upward extension F of the frame F is a cylinder J containing a piston J connected by a rod J to the upper end of the carriage G to move the latter upon the guideways F Metered hydraulic fluid is fed into the cylinder above the piston to move it downward against opposition of fluid below the same which is ejected by the higher pressure of said metered fluid. In this way the grinder wheel I is moved into engagement with the-tooth of the broach which is in registration therewith. The grinder unit H is also reciprocated on the transverse guideways G preferably by a second hydraulic motor K. This motor is mounted on the base portion of the carriage G and has a vertically extending rotary shaft K with an eccentric cam K mounted thereon. The cam K is between parallel bearing faces G on the underside of unit H, so that in each rotation of said cam the motor unit is reciprocated on the guideways G and the grinder wheelis moved longitudinally of the tooth to be ground.

With the construction as described if the teeth to be ground are on a broach type tool, a blank for the latter is mounted on the work table B with its opposite ends engaging the centers B, C. In each position of adjustment of the carriage by indexing mechanism (not shown) the grinder wheel I will be registered with one tooth of the broach. During feeding of the grinder wheel into.

the blank by the hydraulic motor I the motor K will reciprocate it longitudinally of the tool and will grind the back-off surface at the selected angle. The operation will be the same whether the cross sectional contour of the broach tooth is rectilinear or of any desired curvature, such as shown in Figs. 8 to 10, inclusive. In Fig. 8 a pair of spaced grinder wheels I, I are mounted on the same arbor and are fashioned in cross sectional contour to grind opposite sides of a multi-toothed broach L. In Fig. 9 portions of two teeth L are simultaneously ground by the grinder wheel I In each case the angle of the guideways G will move the grinder wheel to produce the desired angle of back-01f, indicated at L The machine is also adapted for grinding the back-off of teeth other than those on a broach type tool, such for instance as a rotary cutter.

What I claim as my invention is:

1. A grinding machine for forming cutting edges and back-offs on tools; comprising a bed, a tool holder and a formed grinder wheel mounted on said bed for relative adjustment in a plane with the plane of rotation of the grinder wheel coincident with the plane of relative adjustment, the mounting for said grinder wheel including a support, a frame pivotally mounted on said support to be angularly adjustable in a plane parallel to said coincident planes, a motorized unit including said grinder wheel, means mounting a portion of said unit on said frame for movement in said parallel plane in a first direction to feed said grinder wheel towards a tool in said holder and for movement in a second direction transverse to said first direction and longitudinally of said tool,

means for moving said unit in said first direction, means for reciprocating said unit in said second direction to form a cutting edge and back-off therefrom on said tool, and means for angularly adjusting said frame to determine the angle of said back-off.

2. The construction as in claim 1 in which said support is a housing and said pivotal mounting of said frame is formed by a hollow trunnion engaging a circular opening in a wall of said housing, said motorized unit passing outward through said hollow trunnion.

3. The construction as in claim 1 in which the cross sectional contour of said formed grinder wheel corresponds to the contour of said cutting edge and the cross sectional contour of the back-off therefrom.

4. The construction as in claim 1 including metered fluid actuated hydraulic motors for operating said unit in the respective directions.

5. The construction as in claim 4 including a carriage on which one of said, tool holder and grinder wheel, is mounted adapted for successively registering portions of said tool with said grinder wheel to form cutting edges and back-offs.

'6. A grinding machine for forming cutting edges and back-oifs on tools; comprising a bed, a tool holder and a formed grinder wheel mounted on said had for relative adjustment in a plane with the plane of rotation of the grinder wheel coincident with the plane of relative adjustment, the mounting for said grinder wheel including a support, a frame pivotally mounted on said support to be angularly adjustable in a plane parallel to said coincident planes, a carriage and a motorized unit including said grinder wheel on said carriage, means mounting said carriage on said frame for movement in said parallel plane in one direction to feed said grinder wheel toward a tool in said holder, and means mounting said motorized unit on said carriage for movement in said parallel plane in a direction transverse to said one direction and longitudinally of said tool, means for moving said carriage in said one direction, means for reciprocating said unit in said transverse direction to form a cutting edge and backoff therefrom on said tool, and means for angularly adjusting said frame to determine the angle of said back-01f.

7. The construction as in claim 6 in which said support is a housing and said frame is pivotally mounted on 4 said housing therewithin, said pivotal mounting of said frame including a hollow trunnion engaging a circular opening in a wall of said housing, said motorized unit passing outward through said hollow trunnion with the grinder wheel disposed exteriorly of said housing.

8. The construction as in claim 6 in which the means for moving said carriage and the means for reciprocating said unit comprise metered fluid actuated hydraulic motors operatively connected to said carriage and mot0rized unit respectively.

9. A grinding machine for forming cutting edges and back-offs on tools; comprising a bed, a tool holder and a formed grinder wheel mounted on said bed for relative adjustment in a plane with the plane of rotation of the grinder wheel coincident with the plane of relative adjustment, the mounting for said grinder wheel including a support, a frame pivotally mounted on said support to be angularly adjustable in a plane parallel to said coincident planes, means mounting said grinder wheel on said frame for movement in a first direction to feed said grinder wheel towards a tool in said holder and for movement in a second direction transverse to said first direction and longitudinally of said tool, means for moving said grinder wheel in said first direction, means for moving said grinder wheel in said second direction to form a cutting edge and back-01f therefrom on said tool, and means for angularly adjusting said frame to determine the angle of said back-ofi.

References Cited in the file of this patent UNITED STATES PATENTS 2,821,815 Banko Feb. 4, 1958 

